A power supply or power sourcing equipment (PSE) in accordance with the Power-over-Ethernet (PoE) standard uses Ethernet cables for supplying direct current DC voltage to powered devices (PD) like lighting devices or the like. Power-over-Ethernet systems are defined in IEEE 802.3.af and IEEE 802.3.at standard. The Power-over-Ethernet systems allow a DC low voltage supply over low cost Ethernet cables (Cat5/6 cables). The Power-over-Ethernet system according to the IEEE standards allows a power of up to 25.5 W (at 42.5 V-57 V). In other words, an Ethernet network cabling environment is used as an independent DC power supply.
US 2012/0223650 A1 discloses a Power-over-Ethernet system for supplying lighting devices as powered devices with energy.
As Power-over-Ethernet power supply systems are believed to become more and more important in the upcoming years, the power efficiency of such power supplies should be improved.